Construction Of Carbon-based Nanomaterial Via The Energy-releasing Effect Of NaN₃ For The Application In Catalysis

Since the 21 century,with the rapid development of industry and the over-exploitation of fossil fuels,energy shortages and environmental pollution have become increasingly serious,thus the development of renewable energy technologies has become urgent.Carbon-based nanomaterial is a kind of environmentally friendly material,which has greatly promoted the development of clean energy due to their unique structure and physical and chemical properties,and it gained a wide range of applications in the field of energy storage,energy conversion and catalysis.In the past two decades,the functionalization of carbon-based nanomaterials has aroused great attention in the field of Material Science and Chemical Engineering.Currently,the basic research direction on carbon-based nanomaterials lies in the exploration and development of fundamental research,the establishment of new research methods and new experimental techniques,and the promotion of cross-cutting multidiscipline.In this research,we will focus on combining two fields of Energetic Materials?EM?and Advanced Materials?AM?,and proposing a strategy of EM-to-AM,aming at using the energy-releasing effect of energetic materials to construct the carbon-based materials.Energetic materials have a high energy density,they will release huge heat and produce abundant active substances during the process of releasing energy,such as oxidants,reducing agents,free radicals and high-kinetic energy fragments.The special environment can be applied to the synthesis and functionalization of many types of advanced materials.The proposed strategy provides more possibilities for interdisciplinary basic research and extended applications in the field of energy storage and conversion.Based on the EM-to-AM strategy,all research works in this paper involve one type of energetic material,which is sodium azide?Na N₃?.Na N₃is a type of nitrogen-rich energetic molecule with high energy density and simple composition,which is an ideal choice in application of EM-to-AM strategy.This research aims at developing the multiple energy-releasing effects of Na N₃,such as high capacity of heat,nitrogen-rich characteristics,high energy density of N₃^-and the strong reducing property of sodium clusters.The use of different energy-releasing effects can optimize the controllable synthesis,doping and structural modification of carbon-based nanomaterials,and provide better performance in the field of photo/electrocatalysis.Therefore,it is a significant project to use the energy release effect of Na N₃ to achieve construction of new carbon-based nanomaterials.The main research results are summarized as follow:?1?Graphite carbon nitride?g-C₃N₄?is a kind of non-metallic semiconductor photocatalyst.However,the problems of g-C₃N₄ with low visible light utilization and high recombination of photo-generated carriers remain to be resolved.In this work,we use the deflagration of Na N₃ to modify the electronic structure of g-C₃N₄,and construct nitrogen vacancies in g-C₃N₄ by a controllable concentration.Experimental and DFT results have shown that the introduction of nitrogen vacancies greatly broadens the spectral absorption range of g-C₃N₄ and promotes the separation of photo-excited electrons and holes.The photocatalytic performance results show that the nitrogen-defective g-C₃N₄ shows a high-efficiency degradation of rhodamine B.Therefore,the Na N₃deflagration is an effective strategy to construct nitrogen vacancies and achieve energy band regulation of semiconductors.?2?The development of non-metallic carbon-based nanomaterials with high density of active sites and large specific surface area arouse wide attention in the field of electrocatalysis.In this work,applying Na N₃ deflagration with mixing carbon source of pentachloropyridine?C₅Cl₅N?,a nitrogen-doped carbon nanosphere with a hollow structure can be quickly prepared in a closed environment.Combined with the post heat treatment,the formed materials?DAC-Nt?possess appropriate amounts of defects and surface nitrogen doping.Studies have shown the DAC-N800 has excellent onset potential of 0.89 V vs.RHE,which is reported to be one of the best ORR catalyst.This work shows that the Na N₃ deflagration is a fast,simple and high-yield method to the synthesis of metal-free carbon-based nanomaterials.?3?Metal organic framework?MOF?is a kind of coordination polymer with ordered porous structure and large specific surface area,which can be applied as a precursor to design derivative materials with various structures.In this work,ZIF containing Zn and Co is used as the precursor,and a composite material with carbon-coated metal nanoparticle structure can be quickly prepared by the deflagration of Na N₃ in a closed environment.In order to further improve the dispersibility of Zn O/Co-C nanoparticles,graphene oxide is used as the carrier in the post heat treatment,and the graphene-supported metal nanoparticle material?Co-C@r GO?exhibit good ORR catalytic performance?onset potential:0.85 V vs.RHE?.The research work shows that the utilizing the high capacity of heat of Na N₃ deflagration is an effective strategy for the rapid carbonization of polymers and the rapid preparation of multifunctional derivatives.?4?In recent years,developing novel coordination polymers and study their applications is of great significance.This work applied hydrothermal reaction,using Na N₃ as the nitrogen-rich energetic ligand and successfully constructed several nitrogen-rich hierarchical coordination polymers.Studies have found that the prepared CPs contain high nitrogen content?54.6?59.65 at%?and large specific surface area.Infrared spectroscopy shows that the prepared polymers all contain energetic ligands?N=N=N?,especially the Ni-e MOF.The results indicate that the prepared coordination polymer not only contains a high nitrogen content,but the energetic ligands also enables it to own a high density of energy.It shows the Na N₃ is an ideal precursor for the preparation of high-nitrogen coordination polymer.?5?This research work is based on the utilization of Ni-e MOF prepared in part?4?,which is used as the precursor in this work to produce derivates.A simple one-step low-temperature pyrolysis?450??is used to prepare graphitic carbon coated Ni₃C/Ni nanoparticles composite with high content of nitrogen.The prepared product Ni₃C@Ni-C has good ORR performance?onset potential:0.82 V vs.RHE?,and exhibits superior stability and methanol resistance.The significance of this work lies in the rational use of the prepared nitrogen-rich energetic coordination polymer,a method of low-temperature synthesis of producing transition-metal carbides materials is achieved.